docs: def process_tokens(self, tokens):
          """Process the token stream.
  
          This is required to override the parent class' implementation.
  
          Args:
              tokens: the tokens from the token stream to process.
          """
          for tok_type, token, (start_row, start_col), _, _ in tokens:
              if tok_type == tokenize.STRING:
                  # 'token' is the whole un-parsed token; we can look at the start
                  # of it to see whether it's a raw or unicode string etc.
                  self._process_string_token(token, start_row, start_col)